On June 18, Mayer says she got a call: "I’m doing a CEO search. It’s a Fortune 500 company. It’s in the consumer Internet space. It’s in Silicon Valley—you wouldn’t even have to move. It’s the perfect job for you. The board is asking for you by name. Are you interested? It’s Yahoo."

She says she had gotten calls like that before, and always turned them down. "But this time it was Yahoo, and that changed everything," says Mayer, because, "Yahoo defined the Internet."

While she was excited about the job, she had one giant apprehension. She was pregnant.

"After 13 years of really hard work at Google, I had been envisioning a glorious six-month maternity leave," she said. If she became CEO of Yahoo, "a long leave couldn’t happen."

She decided to forego the long leave and take the job.

To take on the CEO role, and have a child at the same time, Mayer realized, "that there wouldn’t be much time beyond my job and my family for anything else," but, "I decided I was fine with that, because my family and my job are what really matter to me."

On July 11, she got another call: "You… should be smiling. You are the next CEO of Yahoo."

She says she knew it was risk, but, "New beginnings – professional, personal, or come what may – are always uncomfortable, but being open to them is the only way to grow. In the end, we are all capable of so much more than we think."

While this is an inspirational tale, we should mention that Mayer was in a unique position. She was able to build a nursery in her office. And she's a multi-multi millionaire from her days at Google. Taking on a new, challenging job isn't always an option for women about to give birth.

However, the moral of the story remains the same: Don't be afraid to get outside of your comfort zone when once-in-a-lifetime opportunities present themselves.